693 at DDP yesterday

My '07 made 722hp running Flux 2.5's with the small BD tow twin setup. I'm pretty sure we could have got 750hp out of it with a bit of tuning...
I wouldn't be so sure that your lack of power is completely related to your turbo sizing.

Those 40" tires are robbing power...Remember that the dyno only measures your trucks ability to accelerate the rollers...It does not take into account the fact that the truck must also accelerate the weight of those monster 40's!
 
I'm betting at best with the tires he's losing 25hp so I doubt that's his problem. It's definitely not 100hp or so.
 
Dockboy said:
One of the worst mistakes people make is trying to correlate more boost with more airflow :poke:

You need more air, not more boost ;) Remember, the max airflow in a compound setup is determined, and limited by the capabilities of the primary. The compounded boost value is merely a function of the primary boost compounded by the pressure ratio of the secondary turbo. Increasing the total boost by running the chosen turbos out of their efficiency merely creates more heat and higher drive pressures, not more air ;)
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yup!! This is why I have the GT42 limited to 30 psi, with the HX40 pushing total to 54. At that pressure, I clean up on the top end...I am out of fuel!!
Dual external gates allow me to run boost from 28 psi all the way to 60 if need to. The top turbo never exceeds a 2.4:1 absolote pressure ratio.
 
Diesel Freak said:
yup!! This is why I have the GT42 limited to 30 psi, with the HX40 pushing total to 54. At that pressure, I clean up on the top end...I am out of fuel!!
Dual external gates allow me to run boost from 28 psi all the way to 60 if need to. The top turbo never exceeds a 2.4:1 absolote pressure ratio.
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so you have a wastegate before and after the HX40, then its just being dumped and not used again? sounds like a good setup, how is it on the street?
 
i don't disagree with you and thanks for the thoughts on the matter. i think we got some progress today. byron and i tightened the wastegate rod 8 rotations. it did turn out the drivepressure was opening the wastegate whenever it wanted to. it had little tension on the wastegate rod. we also got the bottom turbo gauge on.

with the boost bolt wide open and loose wastegate:
i was seeing 59 psi overall.


with the boost bolt still open and the wastegate rod tightened:
WOT - 67psi overall and bottom turbo 30psi

30psi overall and bottom turbo is 10
20psi overall and bottom turbo is 5



curious to hear everyones thoughts and what they think i can run my plane jane s400 at. i can play with the boost bolt now if recommended.

many of you are on the right path and thank you for the info trying to help.
 
i'm also guessing that the wastegate was dumping CRAZY EARLY and causing the s400 to run 40+psi. not good and the turbo was running outside of its' effeciency map right?

the truck feels more powerful now with the waste gate tightened.
 
As Dockboy said, more boost doesn't mean not more air flow. IMO, The #'s your looking for are not there with your current setup.
 
maybe so... but with the wastegate rod being loose and the wastegate opening at low boost was not helping my cause!!!

i think the bottom turbo was being way out side of its map because of this.

i just need to know what the boost limit is on the s400 and stay within the map. any help in that area would be helpful.
 
35-37 max for me. The overall starts getting to high at that point and i will go to a larger primary. I try and keep my max boost below 70.
 
now at this point... to bring the primary up about 5 more psi to 35... do i lengthen or shorten the wastegate rod?

i assume loosen right? which will bring my overall boost down, no?

remember, my waste gate linkage was really loose before all this started.
 
DieselheaD said:
so you have a wastegate before and after the HX40, then its just being dumped and not used again? sounds like a good setup, how is it on the street?
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Yep, 38mm gate for the hx40 which dumps backinto the hot pipe. The gt42 has a 50mm gate that dumps to atmo..braaaaaaaaaaaaap.

It runs well for a street setup, not the holy grail for huge power, but it drives as well as the small BD setup, but can handle much more fuel.

70mph in 6th yeilds about 8 psi total with 3 from the GT42

24 psi total and the gt42 is making 7.

I have the 1.15 a/r T4 housing in the 42 and a non wastgated 16 cm H1C housing on the hx40.

If I wanted more air, I would run a 64 on top with 91 on the bottom. :charger:
 
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The sweet spot for the 75mm S400 is 30 psi (see spec sheet I attached on the previous page), since you do not have an intercooler between the turbos, that is where I would keep it.

If you can not keep it below that by indirectly playing with the top gate, you need either a wastgate on the S400, or a bigger turbo or both.
 
cliff, i did see your attachment but i don't understand how to read turbo maps.

thanks for the info... 60 psi. i will play with the boost elbo a little and the priority will be to keep the s400 at about 30psi.

thanks man.
 
Diesel Freak said:
S400 specs posted here. The map is for the 75mm wheel.

If you do have a 71mm S400, then you are out of air, and nothing other than Nitrous will make more power...remember, it's a 2.8 class turbo.

If you have the bigger 75mm S400, it should be making 30 psi. You can push the top turbo to get 70 psi total, but it will be hot!!! Still, for the power you want, a standard 75mm S400 is a bit small.

Call Rip and get a 66mm S300 and a 80mm S400 and give that motor the air it needs!!
Click to expand...

Does Rip's kit use the 75mm as the standard size in his 3rd gen twin turbo kits?
 
Smokin07 said:
Opie,
Are you going to spark up the old 24V?!!
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Right now thanks to Rip & Bill the 05 Maxipad is the next one to get sparked. However, I did by a set of turbos and a dyna80 from Bill for the 01. It still needs about a month straight of my time before it will be ready for reassemble. No expense of research time and money has been spared with that truck.lol
 
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